Following the publication, the Historical Enquiries Team, and more recently PSNI detectives in Serious Crime Branch, began a review of the case.

Solicitor Kevin Winters said the families were suing the government and its agencies at the High Court over "deliberate misinformation spread by the authorities both in the immediate aftermath of the killings and for many years thereafter".

"In the absence of a meaningful response from the chief constable to the ombudsman's findings and in the continued police denial that 'investigative bias' did take place, the families have been left with little choice but to proceed with this litigation," he said.

A 69-year-old man arrested in connection with the attack was released unconditionally on Wednesday.